Dialkyl fumarate-vinyl acetate copolymers



United States Datent DIALKYL FUMARATE-VINYL ACETATE COPOLYMERS Edward P. Cashman, Bayonne, N. J., Ethel J. Corcoran (Guzy), New York, N. Y., and Raymond M. Dean, Westfield, N. J., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application May 6, 1954, Serial No. 428,122

3 Claims. (Cl. 260-785) This invention relates to a process for the preparation of lubricating oil additive materials and the products prepared thereby. Particularly the invention relates to an improved process for the preparation of pour point depressing additive materials for combination with waxy mineral lubricating oils. More particularly the invention relates to an improved process forrthe preparation of pour point depressing lubricating oil additive materials by copolymerizing an ester of an unsaturated polycarboxylic acid prepared in the presence of a mild esterification catalyst with a second polymerizable material in the presence of a peroxide catalyst in an alkaline medium.

The art of lubricating oil additive manufacture has long been familiar with the preparation of polymers and copolymers to form materials useful for improving desirable characteristics of lubricating oils. Of particular interest in recent years has been the development of additive materials for improving the viscosity index, that is, for reducing the rate of change of viscosity of an oil with a change in temperature, and for improving the pour point of a lubricating oil, that is lowering the temperature at which the lubricating oil loses its property of free flow. Such materials as polymers and copolymers of acrylate esters, polymers and copolymers of alpha-beta unsaturated polycarboxylic acid esters, etc., have been found to be very satisfactory for many purposes. It has also been found, however, that the preparation of these polymers and copolymers presents many technical difiiculties. Foremost among these difliculties is the problem of odor and color degradation experienced, particularly in copolymers of acid esters with other polymerizable materials. Although many theories have been advanced to explain the formation of the undesirable color and odor bodies, the exact cause of this phenomenon is not known.

It has now been found, however, and forms the object of this invention, that copolymers having outstanding utility as lubricant additives may be prepared by a process which eliminates the formation of undesirable odor and color degrading materials Without harming the improving characteristics of the additive materials.

Briefly stated, the improved process comprises the steps of preparing polycarboxylic acid esters in the presence of a mild esterification catalyst and copolymerizing the acid esters so formed with other polymerizable materials in the presence of a peroxide catalyst and in an alkaline medium.

The improved process of this invention is applicable to the polymers or copolymers of esters in general. It has particular advantage, however, when applied to the copoly merization of unsaturated polycarboxylic acid esters with other polymerizable monomeric materials.

Use of peroxide copolymeric catalysts is known in the art. Ordinarily these catalysts are used in neutral or acidic media. So far as is known, this is the first disclosure of the use of a peroxide catalyst in an alkaline medium, the advantages obtained being pointed out in detail below.

The unsaturated polycarboxylic acid esters may be represented by the following formula wherein (1) A and D are carboxylic acid ester groups (-(JOR) and B and E are hydrogen, e. g., fumaric acid esters, maleic acid esters, etc., or (2) A and D are carboxylic acid ester groups, as above, and either B or E is a methyl group, the other being hydrogen, e. g., citraconic acid esters, mesaconic acid esters, etc., or (3) A and B are hydrogen, D is a carboxylic acid ester group and E is a methylene carboxylic acid ester group,

e. g., itaconic acid esters, or (4) A and D are carboxylic acid ester groups as above, E is a methylene carboxylic acid ester group and B is hydrogen, e. g., aconitic acid esters.

It will be noted that the unsaturation in all of these compounds is alpha-beta to at least one carboxy group. Although any of the polycarboxylic acid esters, according to the formula above, or mixtures of such polycarboxylic acid esters, are operable in the process of this invention, the fumaric acid esters and maleic acid esters are partic ularly advantageous. unsaturated polycarboxylic acid esters in varying proportions, i. e., 10-90 parts fnmaric and 90-10 parts maleic ester, may be used in place of only one ester.

The esters may be prepared by esterification of any of the unsaturated polycarboxylic acids or their corresponding anhydrides with which the art is familiar.

The alcohols used in preparing the esters of the polycarboxylic acids or their anhydndes are selected from the C to C aliphatic alcohols. Primary alcohols are preferred over secondary and tertiary alcohols, although secondary alcohols are sometimes suitable. The alcohols are preferably saturated, although some degree of un saturation is permissible when mixtures of alcohols are employed. Straight chain or lightly branched alcohols are preferred over highly branched alcohols.

In the alcohols selected for preparing the esters, there should be sufficient hydrocarbon content to insure solubility of the final polymer products in lubricating oils, which in the case of most oils requires that the alcohols have on the average at least about 7.5 carbon atoms per molecule. When employing single alcohols those ranging from C to C are suitable. When mixtures of alcohols are employed, those ranging from C to C can be used in such proportions that the average is about C or greater.

In general, the products prepared according to the invention are both pour point depressants and viscosity index improvers. However, for optimum potency it is usually desirable to select the alcohols used in preparing the esters so that the product will be primarily a pour point depressant or primarily a viscosity index improver. For optimum pour depressing potency in a wide variety of mineral lubricating oils the alcohols should have on the average about 11 to about 15, preferably 11.5 to 14, carbon atoms per molecule. For optimum potency as a viscosity index improver, the alcohols should have on the average about 7.5 to 11, preferably 8 to 10, carbon atoms per molecule. Exceptions are sometimes found; for example, products prepared from relatively short chain alcohols are good pour-depressants in relatively Patented Mar. 4, 1953 Mixtures of two or more of such Among the alcohols that may be mentioned specifically as having utility in this invention are octyl, isooctyl, 2- ethylhexyl, nony1,;2',2,4;4-tetramethylamyl; decyl; dodecyl tetradecyl, cetyl, and stearyl alcohols. Mixtures of the above are operable so long. as. the components of the mixture are adjusted so that the average number ofcarbonatoms' of themixture is-betweenS and-about 18 carbon atoms. Thus, methyl alcohol=-'may -he' admixed with stearyh alcohol to obtain" a mixture havingarr average side chain length within: the desired range.

Oneespecially desirable mixture of alcohols operable in thisinvention is the commercially available-mixture known as liorol-7'-alcoholandohtained byhydrogenation and" refining of coconut oil; The distribution the alcohols of this mixture and other commerciallyavailable alcohols are shownin the following table:

COCONUT 'OIL ALCOHOL CARBON CONTENT the instantv invention contemplates the copol'ymeri'zation. of the polycarboxylic. acid esters as. describedahove withother polymerizable monomericmaterials- These. monomers may .besrepresented. by the following formula:

wherein (l) Xis hydrogen.an,d Y is anester-"group- R. being; methyl, ethyl, butyl: and the-:like) e. g.; vinyl acetate, vinyl butyrateandtheslike; or

(2-') is methyl, ethyl,. etc.,. andi'Yi isas" descrihed above,

e; g; isopropenyllacetate; etc:, or

(3)v is-a halogen: andrY isms described above, e. -g.,

alpha'-.chlorovinylracetate, etc.,..or

(4), X is; a. hydrogen" orzmethyl and Y istan aromatic group, e;. g., styrene, alpha-methyl styrene; and the like, or

(5) X is hydrogen of methyl and Y is --CEN, e; g.,-

acrylonitrile, etc.

Although any' of the polymerizable monomeric. materialstypifiedby'theformula above are operable to form useful copolymers" with the polycarhoxylic acid esters outlined above, the preferred embodimentcontemplates the-use of vinyl compounds; particularly vinyl esters and" th'eihsuhstitution products: Vinylfatty'acid'esters containing from about 2 to-about-18 carbons'are'particularly operable, such: as vinyl acetate; vinyl propionate; vinyl butyrate, vinyl? laurate, vihyl stearateand the like: Mix= tures of" such vinyl esters; or -g., l0-90"part's-of vinyl" acetate-and 90-10 parts: of isopropenyl acetate; :may' be' used, in. placeof; a relatively" pure vinyl ester. Vinyl" acetate: istpa-rticularly preferred;

As waststatedubrieflyzabove, the instant invention're .the' polycarboxylic acid ester.

Sodium acid sulfate is preferred. This esterification step is generally carried out i1r.the'. presence of'a Water entrainer, such as heptane, naphtha,'benzol, xylol and the like. From aboutlfito. about 2.5,mo1ls of the esterification agent is added per mol of the polycarboxylic acid .and'the. reactants are refluxedat atemperatureofi about 200.1to 300 F.. for a period. oftime suflicient: to. reduce. the neutralization. number of the. reaction. mixturev to below about 5.0.. Ordinarily thistakes from about. 2 to .10 hours: The water entrainer may thenbe stripped from. the mixture by distillation under vacuum'and'.the. ester recovered.

The secondstep of the inventive process involves the copolymerization. of the monomer prepared-asgenerally describedabove with a second polymerizahle material; preferably the CQ-C esters of fatty acids exemplified by'vinyl" acetate; In' prior art processes, this copol'ymerization'has been c'arried"out'with.the aid of various polynrerization catalysts of the peroxide type. "In the instant process: these same general typesiof catalysts" are used; According try-the invention th'ey' are'used in an' alkaline medium-Orin the presence or an alkaline reacting material' exemplified"by such materialsas'sodium'c'arb'onate, barium hydroxide; lime; sodiumhyd'roxide andi'thelike.

Depending upon-'the 'desired' product; the 'nrono'm'ers .in' the copolymerization' reaction utilizingithe process of inventionmay lie-varied greatly. However, whe'na cof polymer of a polycarboxylicacidester and vinyl acetate is being prepared; itis desirable that'from 2% to 40% of" vinylacetate; preferably 1 0% to 25%, be used with A 'copolymer of='% dicarhoxylic acid-ester with 20% vinyl acetate-has outstanding pour depressant qualities.

The process of the instantinventionzmay"be applied toany on the well known polymerization techniques. For

instance; the: bulk polymerization: technique wherein the catalyst used' i's added directly to flae mixture ofthe monomers: alone -may be used applying the processof invention. lf it is desired; the solution polymerizationtechnique maybe-utilized, that-is; the techniqueinwhich the monomers arepol ymerized in=solution*in-asolvent-fer example naphtha; lubricating oil' fractions, white oils, benzene, toluene and other-petroleum hydrocarbons, as well as esters, ethersand-chlorinated solvents such as chloroform; carbon tetrachloride; etc. When the solution polymerization technique is used; it is preferred thatthe monomer'concentration' in the diluent range from-30% to 99% hyweight, b'asedonthe weight of the total mixture; The suspension technique ofpolymerizati'om or theemulsio'n'polymeri'zation technique" wherein an-ernulsifyingagent such as a soapis used to form' an emulsion of the monomersv and water and a water soluble catalyst is utilized mayalso' be adapted t'o the process ofiihvention-withexcellentresults:

The: reaction conditions to-beexperiencedirr the copolymerization" may also bevaried within wide" ranges.

In the preferred* embodiment; the copolynrerization'of polycarboxylic acid esters with otherpolymeri'zable ma.-

found advantageousto utilize from"0l05% to 3% weight, based on the weight of the monomers, of a peroxide catalyst, with 0.1% to 2.0% by weight being preferred. The peroxide catalysts may be added at the start of the reaction, in small portions at the early stage of the reaction, or during the entire course of the reaction. In general, milder copolymerization conditions are obtained with lesser amounts of catalyst or if the catalyst is added in small portions during copolymerization. Among the operable catalysts are hydrogen peroxide, benzoyl peroxide, cumene hydroperoxide, potassium persulfate, lauroyl peroxide, ammonium persulfate, urea hydroperoxide, tertiary butyl hydroperoxide, tertiary butyl perbenzoate and the like, benzoyl peroxide being used in the preferred embodiment. Reduction-oxidation activators known by the name of Redox, for example, benzoin and ferric laurate, may be used if desired.

The time of the reaction may vary from 1 to 50 hours, with from 3 to 24 hours being generally suflicient.

As was stated above, the prior art processes concerned with the preparation of polycarboxylic acid esters teach that an acidic catalyst, preferably a strongly acidic catalyst such as sulfuric acid is used to aid in the ester formation. With the instant invention the use of a mild esterification catalyst with or without a water wash of the resultant ester, followed by the copolymerization of the monomers in the presence of a peroxide catalyst in alkaline media, practically eliminates the color and odor degradation of the material on storage. As will be pointed out more in detail below, use of a sulfuric acid catalyst followed by water washing, or use of a mild catalyst without polymerization in alkaline media does not give the highly stable products desired, and obtainable with the inventive process.

A second advantage of the invention is that according to this procedure, less of the peroxide catalyst is used in the polymerization step with obvious advantages.

The invention will be more clearly explained by reference to the following illustrative examples.

Example 1 Lorol 7 fumarate was prepared from the following reactants:

108 lbs. Lorol 7 alcohol (2.15 mols) 28 lbs. fumaric acid (1.0 mol) 315 gms. sulfuric acid (catalyst) 40 lbs. heptane (water carrier) The reactants were refluxed at 250-260 F. and the water of esterification was separated and withdrawn from the reflux stream. When the neutralization number of the reaction mixture was less than 5.0, the heptane was stripped at 250260 F. under vacuum (50 mm. Hg).

One hundred twenty (120) lbs. of the resultant product was mixed with 29.5 lbs. of vinyl acetate (distilled to remove commercial stabilizers) and the temperature adjusted to 155-160 F. A total of 840 gms. of benzoyl peroxide catalyst were added in 5 equal portions over 5 hours during which time the temperature was permitted to rise to 170 F. The copolymerization was continued for an additional 5 hours at 170 F. Forty-six (46) lbs. of oil were added to the reaction mixture in order to stop copolymerization.

Example 2 Lorol 7 fumarate was prepared from the following reactants:

The ester was prepared in the same manner as in Ex ample 1 except that an esterification temperature of 290 300 Ffwas used.

One hundred twenty 120) lbs. of the resultant product was mixed with 29.5 lbs. of vinyl acetate (distilled to remove commercial stabilizers) and the temperatureadjusted to 155l60 F. Three hundred thirty-six (336) Example 3 Lorol 7 fumarate was prepared from the following reactants:

208 lbs. Lorol 7 alcohol (2.13 mols) 54.5 lbs. fumaric acid (1.0 mol) 635 gms. sulfuric acid (catalyst) lbs. heptane (water carrier) The esterification was carried out in a manner similar to the procedure of Example 1. When the neutralization number of the reaction mixture was less than 5.0, the temperature was reduced to F. Ten gallons of water were added. After agitation and settling, the water was drawn off and the heptane stripped at 250-260 F. under vacuum (50 mm. Hg).

Two hundred thirty-two (232) lbs. of resultant product were mixed with 54 lbs. of vinyl acetate (distilled to remove commercial stabilizers) and the temperature adjusted to 160 F. 6.4 lbs of benzoyl peroxide were added in 13 portions over 12 hours, while maintaining the temperature between 170 F. The reaction was stopped by adding oil to the copolymerization mixture after 13 hours total reaction time.

Example 4 (#19-915) Lorol 7 fumarate was prepared from the following reactants: 108 lbs. Lorol 7 alcohol (2.15 mols) 28 lbs. fumaric acid (1.0 mol) 318 gms. sodium bisulfate monohydrate (catalyst) 40 lbs. heptane (water carrier) The esterification was carried out in the same manner as Example 1, except that a temperature of 270280 F. was used. When the neutralization number was less than 5.0, the temperature was reduced to 150 F. Three (3) gallons of water were added. After agitation and settling, the water was drawn OE and the heptane stripped at 250-260 F. under vacuum (50 mm. Hg).

One hundred twenty-eight (128) lbs. of the resultant product was mixed with 29.5 lbs. of vinyl acetate (containing commercial stabilizer) and the temperature adjusted to 155-160 F. One hundred ninety-two (192) gms. of benzoyl peroxide were added in 3 portions over 3 hours while permitting the temperature to rise to 168 F. The copolymerization was continued for an additional 5 hours at 168-170" F. Forty-six (46) lbs. of oil were added in order to stop the reaction.

Example 5 Lorol B fumarate was prepared from the following reactants: 435.8 gms. Lorol 7 alcohol (2.15 mols) 116.0 gms. fumaric acid (1.0 mol) 2.9 gms. sulfuric acid (catalyst) 160.0 gms. heptane (water carrier) The esterification was carried out in the same manner as in Example 1, except that a temperature of 260-280" F. was used Five hundred six (506) gms. of the resultant product were mixed with 121 gms. of vinyl acetate and 2.0 gms. of sodium carbonate. 19.6 gms. of benzoyl peroxide were added in 7 portions over 18 hours at 160180 F.

justed to 155-160 F. onejhundree eiglir'y'atreecfss)" gms. of sodium carbonate were added. Severity-two (.771) gms. of benzoyl peroxide wereadded' in zper'tiens in" one hour permitting the temperature toriseto 164". F. The copolymerization was continued: for anadditional. 11-

hours at 160470 F. Forty-six=( 46-) -lbs. of-oil: were added in orderto stop copolymerization.

Example 7 Lorol 7 fumarate was prepared as-in Example 4. One hundred twenty-eight (128) lbs. of the resultant product were mixed with 29 lbs. ofvinyl acetate'.(containing= commercial stabilizer) and the temperature adjustedto 155-160? F. Three hundred sixty (360) gms.- of barium: hydroxide pentahy'drate wereadded. One hundred sixtyfour 164) gms of benzoy] peroxidewere added: in 3 portionsv over- 3 hours permitting-the temperature to rise to 168 F. The copolymerizationwas continued for an additional 2% hours at 165-170 F. Forty-six (46) lbs. of oil were added' in' order. to stop the reaction.

The materials prepared in the above examples were blended-to 20.0% concentration in' an SAE'ZO grade base oil. These blends were then submitted to fthe' standard viscosity determinations acc'or ding to --ASTM procedure. They were also tested-for color i'n th'e Tag Robinsorr color test according to known procedures and examined for their odor charaeteristics.- The'blends were then stored at 160 F. for a considerable period of time and the color and odor test repeated. The p'our depressing-potencywas then measured in" accordance "with known-procedures: The data'obtain'ed are setou'tin Table 1 below.

eral-l y senewhat higher,

m min-resumedamn-aster accordance wr e d est'rifibaifon catalyst, s used. Siilfuric acid was again a water-wasting step; and a "received wim both tal'y'st and 'the' when washing 'esses" which improvenre come: and odor-stability er the copolyriierswo'mpris'e the-steps er esteriryin i materials at the class of alpha-beta unsaturated polycarboxylic acids and their anhy dride's; preferably dicarbo'xylicl acids; with a lonych'ain aliphatica 'ohtilj pr 'fcr'ably'orie having-{rem 8 to 18 carbon ato'riisper meieeule; 'Tlieest'erfifiif:a'ti'on' catalyst used rariti s-rep er'thepreaess is-a mild'catalyst such as sodiuiii 'acizrsulrare' p tblr'ieiie s'iilplio'nie acid, phosphoric acid and the like. After the esterification step, the ester is polymerized with a low molecular weight vin'yl compound; i preferably es'ter 'liaving' from i th 18 carbons atoms in the alkyl group thereof. Thi's"co'- polymerization step is' carriedout 'inthe presence of=an-- alkaline agent which is preferably a basic material such .as sodium carbonate, calcium hydroxide, barium hydroxide, sodium hydroxide and the like. Ordinarily from 98% to 60% of the acid ester will be copolymerized with TABLE I [Inspection data on til ends of '20 wt; percent cofiolynier rfi sanm'graae inseam Preparation Exampll Example 2' E xample3 niampiea I Examples Examplefi" ExampleT Esterification Gatalyst; Strong 1 Stro -Stron'g Waterwash-ofEster No.'. Yes Nfo. Alkaline Mediator Copolymeri- No zationi lmpectio n s Viscosity. SSU@210F tat-127.3 1-18 10'2-.-2- 115,0 88 155.3 193.3. Robinson Color t. 1% 5 /6 t. 1% 9V 3% 10%; v i Odor Type .sharp, punvinyl acetate, vinyl acetat a sharp pun vmylaeetate; vinyl acetate,

ge'nt vinyl sweet, oily. acetic acid.- tate sweet -i -gent y n-yl 1 sweet, oily. sweet, oily; acetate aceoily. acetate ace- -24tic-acldp '14 14 14tic aci 2 14 Days f5torage @"16flF' 4-; Rob. Color after Storage ts re; 9% 9%; 7%. Odor Type after Storage sharp punsharp, puns1t. vinyl acesharp punvinyl acetate, vinyl acetate, gentv'in'yl gent vinyltate,-sweet,; 'gentjvmyl sweet, oily; sweet-oily."

acetate acetate oily. acetate acid. hstrougacetie a St 868MB ac t acid. ASTM Pour Potency:

Perefrgt in A" Test Oil 9 2% to 40% by weight of the low molecular weight vinyl compound. From 0.2 to 2.0% by weight of benzoyl peroxide catalyst is used and from 0.4% to 1.5% by weight of the basic material is used. Best results are obtained by copolymerization temperatures within the range of from 100 to 200 F.

What is claimed is:

1. An improved process for the preparation of lubricating oil additive materials which comprises the steps of esterifying fumaric acid with a substantially saturated primary monohydric aliphatic alcohol having from 8 to 18 carbon atoms per molecule in the presence of a mild esterification catalyst selected from the group consisting of sodium acid sulfate, p-toluene sulfonic acid and phosphoric acid to form a diester, and copolymerizing about 98% to 60% by weight of said diester with about 2% to 40% by weight of vinyl acetate in an alkaline medium in the presence of a peroxide catalyst, said alkaline medium being produced by the presence of about 0.04 to 1.5 wt. percent, based on the weight of the monomers, of a compound selected from the group consisting of sodium carbonate, barium hydroxide, calcium hydroxide and sodium hydroxide.

2. A process according to claim 1 wherein said peroxide catalyst is benzoyl peroxide.

3. An improved process for the preparation of lubricating oil additive materials which comprises the steps of esterifying fumaric acid with a substantially saturated primary monohydric aliphatic alcohol having from 8 to 18 carbon atoms per molecule in the presence of a mild esterification catalyst selected from the group consisting of sodium acid sulfate, p-toluene sulfonic acid and phosphoric acid to form a diester and copolymerizing about 80% of said diester with about 20% of vinyl acetate at a temperature within a range of about 100 to 200 F. in the presence of about 0.2 to 2.0% by weight, based on the weight of the monomers, of benzoyl peroxide catalyst and in an alkaline medium produced by about 0.04 to 1.5 wt. percent, based on the Weight of the monomers, of a highly alkaline inorganic compound selected from the group consisting of sodium carbonate, barium hydroxide, calcium hydroxide and sodium hydroxide.

References Cited in the file of this patent UNITED STATES PATENTS 2,410,089 Lundquist et al. Oct. 29, 1946 2,544,691 Kugler et al. Mar. 13, 1951 2,602,048 Michaels et al. July 1, 1952 2,666,746 Munday et al. Ian. 19, 1954 2,672,446 Mixon et al. Mar. 6, 1954 

1. AN IMPROVED PROCESS FOR THE PREPARATION OF LUBRICATING OIL ADDITIVE MATERIALS WHICH COMPRISES THE STEPS OF ESTERIFYING FUMARIC ACID WITH A SUBSTANTIALLY SATURATED PRIMARY MONOHYDRIC ALIPHATIC ALCOHOL HAVING FROM 8 TO 18 CARBON ATOMS PER MOLECULE IN THE PRESENCE OF A MILD ESTERIFICATION CATALYST SELECTED FROM THE GROUP CONSISTING OF SODIUM ACID SULFATE, P-TOLUENE SULFONIC ACID AND PHOSPHORIC ACID TO FORM A DIESTER, AND COPOLYMERIZING ABOUT 98% TO 60% BY WEIGHT OF SAID DIESTER WITH ABOUT 2% TO 40% BY WEIGHT OF VINYL ACETATE IN AN ALKALINE MEDIUM IN THE PRESENCE OF A PEROXIDE CATALYST, SAID ALKALINE MEDIUM BEING PRODUCED BY THE PRESENCE OF ABOUT 0.04 TO 1.5 WT. PERCENT, BASED ON THE WEIGHT OF THE MONOMERS, OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF SODIUM CARBONATE, BARIUM HYDROXIDE, CALCIUM HYDROXIDE AND SODIUM HYDROXIDE. 